Comcast's Congestion Catch-22

An anonymous reader sends us to Telephony Online for a story about Comcast's second attempt at traffic management (free registration may be required). After the heavy criticism they received from customers and the FCC about their first system, they've adopted a more even-handed "protocol agnostic" approach. Nevertheless, they're once again under scrutiny from the FCC, this time for the way their system interacts with VOIP traffic. By ignoring specific protocols, the occasional bandwidth limits on high-usage customers interferes with those customers' VOIP, yet Comcast's own Digital Voice is unaffected. Quoting: "The shocking thing is just how big a Pandora's box the FCC has appeared to open — and it just keeps getting bigger. When the FCC first started addressing bandwidth usage and DPI issues, it quickly found itself up to its knees in network management minutia. Not long after that, it followed another logical path of the DPI question and asked service providers and Web companies about their use of DPI for behavioral targeting. Now it seemingly has opened up huge questions about what it means to be a voice carrier in the age of IP. It's not hard to imagine the next step: What about video? Telco IPTV services are delivered in roughly the same way as carrier VoIP services — via packets running on the same physical network but a prioritized logical signaling stream. Is that fair to over-the-top video service providers?"

Comments

Re:Congestion?

[WhatAmIDoingHere]

Their issue is upload not download.

How much is self intereference?

[nweaver]

If someone is doing very high traffic, enough to get into Comcast's temporary "QOS Low" category, they are probably sending and full rate. If you are sending at full rate, the typical end-host NAT and buffering alone will cause bad quality for VoIP (search for VoIP and BitTorrent for a lot of such tales). There is nothing Comcast's network management really does to affect things in this case anyway.

Comcast's network management should only cause additional VoIP issues when the big transfer STOPS and the VoIP call is made within only a few minutes (before the user's link is reclassed back into the "QoS normal" category).

Re:How much is self intereference?

[nine-times]

From day one, comcast's VOIP has used seperate channels from their internet services.

I'm not sure that's really the issue. I'll admit a little bit of ignorance on the issue, but what would happen to your upload rates if Comcast opened those VOIP channels to normal data? Or what if they allowed VOIP to travel on those channels whether they were the VOIP provider or not?

Because I think the issue is that they're providing a limited amount of bandwidth to the home and complaining about congestion, meanwhile setting aside access for their own services. I can't blame them, since it probably makes them more money, and they're in a position to do it without worrying about competition.

Personally, I think that the companies that provide data infrastructure should be forbidden from providing services. For example, if Comcast is the company that actually strings cable to your house, then they shouldn't be allowed to provide voice, video, or data services over that line. Instead, they should be required to have a set fee that is available to any voice, video, or data provider. So Speakeasy or Earthlink or whoever could effectively lease use of the network for providing services.

I know that whole plan would probably present a number of challenges, but otherwise there's an inherent conflict of interest for any company that provides both infrastructure and services. It's in Verizon's best interest as a phone provider, for example, to hamstring independent VOIP providers if they can, and cable companies likewise have an interest in inhibiting competing video services. Even something like blocking SMTP traffic except to their own servers, which arguably is a valid security precaution, encourages people to use the ISP's email servers, making them more likely to use their ISP email address, making it harder to switch ISPs.

Cable companies and phone companies represent a duopoly, since no one else is really permitted to drop their own independent lines in most places, so you can't rely on competition (i.e. free-market forces) to sort these things out.

All this may sound to some like a bit of a conspiracy theory, but I'm not even claiming that these companies are actually abusing their positions-- or at least not yet. I'm just saying that these represent inherent conflicts of interest, ample opportunities for abuse, and a lack of a free market to allow the "invisible hand" to make things work out (if you believe in that sort of thing). So I think it's time for some improved regulation.

Sorry if this ventures off-topic, but it seemed related to the topic at hand.

To pipe or not to pipe.

[Dyinobal]

Why do ISPs insist on being more than just a pipe? It's so dumb no one wants them to be anything else. Do they just not feel useful when they are a pipe?

Re:Congestion?

[morgan_greywolf]

The problem is that ISP's pay per megabyte for uploads. Downloads are free for them except for the cost of the line and equipment maintenance., etc. That's what this is really all about.

Re:Not agnostic

[Trekologer]

But Comcast does not. Comcast Digital Voice rides the same channel as cable modem. The only real difference between CDV and another VoIP product (ie Vonage, etc) is that the ATA is built into the cable modem.

Not an easy issue (or set of issues)

[N7DR]

I don't want to spend an hour writing a treatise on this, but I do think I need to make a few things clear.

Several issues are convolved here, and the "right" answer to each individual issue is not obvious (at least not once one factors in political and business viewpoints), so the convolution is essentially a mess. Like the original poster of the story, I have to assume that the FCC decided intentionally to delve into the mess. Anyway, here are the real issues:

1. There is (as far as I know) no new technology here. The PacketCable specs, which define how cable operators (most of them, anyway) implement VoIP were released in 1999. Comcast (like other US cable operators) has been deploying this technology since about 2002. As far as I know, the only part of the spec that Comcast don't really implement is the security portion. In any case, the specs are public and have been so for nearly a decade.

2. There is a fundamental technical difference between over-the-top VoIP (i.e., service provided by a third party such as Vonage) and telephony provided by the cable company.

3. The cable company can differentiate between its VoIP (or any other service needing preferential Quality of Service (QoS)) and ordinary so-called "best-effort" traffic, which is what is used to carry everything else, including over-the-top VoIP.

4. The reason for this is that it is the only entity that has access to the Cable Modem Termination System (CMTS), which controls the microsecond-by-microsecond details of traffic flow over the plant between a customer and the cable operator's facilities.

5. It is reasonable (from the cable operator's point of view) that since it owns the CMTS (and CMTSes are not cheap either to acquire or to manage), it's not voluntarily going to let some other company control any part of its operation (especially since if that gets screwed up, the customer experience is impacted).

6. Looked at from the point of view of guarantees applied to services, this looks like a violation of net neutrality, since over-the-top operators have to fight for bandwidth against things like P2P and web browsing, while the cable operator's phone calls don't have to do so (they have QoS guarantees).

7. But there is no law against violating new neutrality (as far as I know, in the US anyway). IANAL.

8. One can also argue that although it *looks* like a violation of net neutrality, it is in fact not such a violation, since from the viewpoint of what is happening inside DOCSIS (the protocols used to manage bandwidth on the plant between the residence and the cable company), over-the-top VoIP looks completely different from the cable company's offering. From that technical viewpoint, they can be considered two different services, and hence it would (presumably) be fine even under net neutrality principles to treat them differently.

Those are the basic ideas (although of course I've just summarized; it would take a lot more space to really describe all the details). But the basic point here is that there are lots of issues and viewpoints, some business-related, some political, and some technical. And much though one might like to demonize one party or the other, in this particular case the issues don't really seem to lend themselves to such a simple analysis.

Disclaimer: this was a quickly-written post of my initial impressions given the rather sparse (and not unambiguous) information available.

Re:Congestion?

[stonefoz]

Perhaps it doesn't need three tiers, but two would still alleviate real times problems. No, you can't just do router magic tricks on the customers end line, nothing there will affect their incoming traffic, it has to be done at the ISP. X (a much smaller percentage) of realtime bandwidth, and Y (all the rest of it). Customers wouldn't have to configure shit, Skype, Broadvoice and YouTube, etc.. would have to mark TOS on they're outbound. Customers would only have to be informed if they've asked to too much realtime data, opps you've ran out this month, prepare for shitty phone service. We wouldn't guarantee voip service unless the customer had one of our T1's or DSL so that we could throttle non-realtime bandwidth. For Comcast to play fair, they would have to honor other real-time providers QOS settings. Now if the customer "ask" for a bunch of crap off of a misconfigured service, it's there fault they run out of real-time. Two tier bandwidth would be a god-sent.